| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the modulation distortion of a waveguide type semiconductor photoreceptor element which can operates at a high speed by making the quantity of absorbed energy per unit length of a waveguide area which guides light made incident in parallel with a semiconductor layer along a light absorbing layer constant over the entire area of the waveguide area. SOLUTION: A waveguide type semiconductor photoreceptor element is constructed in a multilayered semiconductor structure in which an n-side clad layer 2, an n-side light confining layer 3, a light absorbing layer 4, a p-side light confining layer 5, and a p-side clad layer 6 are successively formed on a semiconductor substrate 1. The light absorption coefficient of the waveguide is decided as the productΓαof the characteristic valueαof the material of the light absorbing layer 4 and a light confining coefficientΓwhich varies depending upon the structure of the waveguide. The absorbed energy of light per unit length is nearly fixed over the entire area of the waveguide by constructing the waveguide in such a structure that the light confining coefficientΓbecomes larger proportionally to the distance from the incident end face.
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